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Fragmenta entomologica Volume 53 (1) 2021 Volume Fragmenta entomologica -

Department of Biology and Biotechnology “C. Darwin”

University Press Fragmenta entomologica, 53 (1): 81–84 (2021) eISSN: 2284-4880 (online version) pISSN: 0429-288X (print version) Short scientific note Submitted: November 9th, 2020 – Accepted: February 9th, 2021 – Published: March 15th, 2021 DOI: 10.13133/2284-4880/455

First records of the Oak bush-cricket thalassinum on three German islands (: , )

Harald Ahnelt1,2,*, Sara Pleitner3, Björn Schulz4

1 Universität Wien, Department für Evolutionsbiologie, Althanstrasse 14, 1090 Vienna, - [email protected] 2 Naturhistorisches Museum Wien, 1. Zoologische Abteilung, Burgring 7, 1010 Vienna, Austria - [email protected] 3 Hochschule Osnabrück, Am Krümpel 31, 49090 Osnabrück, - [email protected] 4 Stiftung Naturschutz Schleswig-Holstein, Eschenbrook 4, 24113 Molfsee, Germany [email protected] * Corresponding author

Abstract We provide the first records of the Oak bush-cricketMeconema thalassinum on the three German North Sea islands , Föhr and , based on monitoring and citizen science. The presence of the Oak bush-cricket on these German islands is probably due to unintentional introduction.

Key words: Orthoptera, Meconema, monitoring, citizen science, range extension.

Introduction There is seemingly a distinct east–west gradient in the abundance of the oak bush cricket in Schleswig-Holstein and Two species of bush-crickets of oc- especially from the western marshland records are extremely cur in Schleswig-Holstein (), the Oak rare. So far, the oak bush-cricket was neither known from the bush-cricket (De Geer, 1773) coastal region, nor from the North (Dierking and the southern Oak bush-cricket M. meridionale Cos- 1994; Winkler 2000; Winkler & Klinge 2019) (Fig. 1). Here, ta, 1860. Both species are characterized by the lack of a particularly the three geest (lower moraine) islands Amrum, stridulatory organ. Instead, they communicate by drum- Föhr and Sylt provide suitable habitats, but no records were ming with the hind legs on a leaf (Harz 1955). They are known till recently. A similar east–west gradient is found on nocturnal and arboreal occurring in woods, hedges, parks the neighbouring Danish Jutland (Fugle og Natur 2020). and gardens and are carnivorous feeding on small (Schumacher 1980). Meconema meridionale was first found in Germany Material and Methods in the 1960s and has since then spread northwards (e.g. Grünitz & Hochkirch 2007; Winkler & Haacks 2019). The three German North Sea islands Amrum, Föhr and Sylt Meconema thalassinum is native to Germany. Both species form a specific landscape (physical region). Contrary to the can easily be distinguished, as M. meridionale is a flightless western mainland and islands south to them that are marsh- bush-cricket with rudimentary wings and M. thalassinum land, these islands are predominantly remains of glacial has fully developed wings and is able to fly. moraines, so called ‘geest islands’ (Schlenger et al. 1969). During the last decades scientists are increasingly As no proofs of the oak bush-cricket were known from utilizing citizen science as a non-invasive method to these islands (Dierking 1994; Winkler & Klinge 2019) collect information related to the distribution of species (Fig. 1) a monitoring survey was started in 2020, specifi- (e.g. Kleitou et al. 2019). Here, we present a combina- cally on Amrum. Additionally, one of us (SP) conducted a tion of field research and citizen scientists’ reports docu- citizen science approach by an appeal in the online news- menting the first records of the oak bush-cricketM. thal- paper ‘Amrum News’. All records were photographically assinum for the three German North Sea islands Amrum, documented. The localities and exact coordinates of the Föhr and Sylt. records are given in Table 1.

81 Ahnelt et al.

Fig. 1 – Distribution of Meconema thalassinum in Schleswig-Holstein (Germany). Solid red line indicates border between the Atlantic (west) and the Continental (east) Biogeographic Regions. Note majority of records are in the zone of the continental climate. From Winkler & Klinge (2019), modified.

Results island, from Wittdün in the south, directly at the ferry pier, over Nebel in the middle of the island, up to Norddorf in To date, 14 records of M. thalassinum from these islands the north (Table 1). The surroundings are characterized by are documented by voucher specimens or by in situ photo- village-typical green structures like gardens, hedges, single graphs. These are 10 records for Amrum, three records for trees and bushes. All villages are located close to the Am- Föhr and one record for Sylt. All records, except one from rum forest area predominantly formed by deciduous trees, Föhr, are from summer 2020 (Table 1). which acts as a connecting structure. Most of the specimens Amrum. On August 5, 2020 a male was collected in Nor- were found at terraces, inside buildings or in gardens. Just ddorf, sitting on the muddy ground in a small wood consist- two records came from natural habitats (Table 1). ing of Alnus, Populus and Betula. This specimen represents Föhr. On July 28, 2020 a female was photographed sit- the first record ofM. thalassinum for the island Amrum. All ting on a bicycle on a public parking site in Wyk (Table 1). records from Amrum come from the three villages on the The surroundings are typical small city habitats (gardens,

82 Meconema thalassinum in German North Sea islands

trees and bushes (e.g. Populus, Salix, Sambucus) grow in close vicinity. The locality is on the north end of the central geest of Sylt. This specimen represents the first record ofM. thalassinum for the island Sylt.

Discussion

Here, we report the first records of M. thalassinum for the three German geest islands Amrum, Föhr and Sylt. The Oak bush-cricket is common in Germany, but records in its most northern part, in Schleswig-Holstein, are patchy. Here, the Oak bush-cricket is mostly found in the eastern upper moraine landscapes. Towards west, on the lower moraine landscapes, records are becoming rare and in the western marshland and coastal regions this species seems to be virtually absent (Dierking 1994; Winkler & Klinge 2019) (Fig. 1). Probably it is overlooked in these areas (Di- Fig. 2 – A male of the oak bush-cricket Meconema thalassinum from erking 1994; Winkler & Haacks 2019). This distribution German North Sea Islands: island Sylt, 09 Sept. 2020, photo H. Ahnelt. pattern roughly corresponds to the border of the Atlantic and the Continental Biogeographic Regions that divides parks, single trees of different species) and the harbour Schleswig-Holstein in a north–south direction (Fig. 1). with frequent car ferry services is located less than 200 m The origin of the Oak bush-cricket on these North Sea apart. Additionally, eight dead specimens were found from islands is not known. Three scenarios seem to be plausible 2015 to 2019, but no exact documentation goes with this to explain the recent occurrence of M. thalassinum on the report (Table 1). These eight specimens (one female and three islands. seven males) represent the first record of M. thalassinum First, the Oak bush-cricket does not produce noisy songs for the island Föhr and the first for the three German North as it is a non-stridulating species and is therefore often diffi- Sea geest islands. cult to locate. Because of its cryptic and nocturnal life style Sylt. On September 09, 2020 a male was photographed this species might be overlooked for several years or decades. sitting inside a hooded beach chair on a private terrace at the Second, the Atlantic climate with its relatively cool sum- north end of Kampen (Fig. 2, Table 1). The surroundings are mers, especially evident on the coastal regions (Christiansen dominated by beach rose Rosa rugosa but also deciduous & Schmidtendorf 1952), influenced the distribution of many

Island Date N/sex Coordinates/location Location Proof Föhr * 2015–2019 7/♂ 54°42’13”N, 8°24’2”E or in building photo, cs 1/♀ 54°41’19”N, 8°32’59”E Föhr 28/07/2020 1/♀ 54°41’29”N, 8°33’57”E parking site photo, cs Amrum * 05/08/2020 1/♂ 54°41’6”N, 8°19’33”E wet wood voucher Amrum 14/08/2020 1/♂ unknown/near Nebel inside a car voucher Amrum 14/08/2020 1/♂ 54°42’10”N, 8°19’27”E in building photo, cs Amrum 15/08/2020 1/♂ 54°51’10”N, 8°19’25”E in building voucher Amrum 15/08/2020 1/♀ 54°37’36”N, 8°23’38”E terrace photo, cs Amrum 15/08/2020 1/♂ 54°39’12”N, 8°21’3”E in building photo, cs Amrum 17/08/2020 1/♂ 54°40’54”N, 8°19’49”E in building photo, cs Amrum 30/08/2020 1/♀ 54°39’51”N, 8°19’28”E humid wood voucher Amrum 31/08/2020 1/♂ 54°51’10”N, 8°19’25”E in building voucher Amrum 08/09/2020 1/♀ unknown/Steenodde garden photo, cs Föhr 09/09/2020 1/♂ unknown/Wyk in building photo, cs Sylt * 09/09/2020 1/♂ 54°57’54”N, 8°20’36”E terrace photo (Fig. 2)

Table 1 – Records of the oak bush-cricket Meconema thalassinum on the German North Sea islands Amrum, Föhr and Sylt, in chronological order. cs – citizen science. * – first record for the respective island.

83 Ahnelt et al. species, possibly also the Oak bush-cricket. East–west and ographischen Stellung des Geestrandes innerhalb desselben. also north–south gradients in the distribution or even range Berichte der Deutschen Botanischen Gesellschaft, 65: 341- borders inside Schleswig-Holstein have been described for 348. Doi: https://doi.org/10.1111/j.1438-8677.1953.tb00733.x various grasshopper species (Winkler & Klinge 2019). Nev- Dierking U. 1994. Atlas der Heuschrecken Schleswig-Holsteins. ertheless, triggered by climate change temperature was ris- Landesamt für Natur und Umwelt des Landes Schleswig-Hol- ing during the last decades and enabled thermophilic species stein, Kiel, 61 pp. Fugle og Natur 2020. Egeggræshoppe. to extend their distribution area in Europe northwards, e.g. Available on-line. Roeseliana roeselii (Hagenbach, 1822) and Meconema me- Grünitz K., Hochkirch A. 2007. Erst-Nachweis der Südlichen ridionale (Orthoptera) (Grünitz & Hochkirch 2007; Hoch- Eichenschrecke, Meconema meridionale (Costa, 1860), in kirch & Damerau 2009). Possibly, climate warming also Bremen. Articulata, 22: 77–79. favoured range expansion of the Oak bush-cricket. Sutton Harz K. 1955. Das Trommeln der Eichenschrecke Meconema et al. (2017) mentioned a northward range expansion of this thalassinum De Geer (Orthoptera, Ensifera). Nachrichten- species in Great Britain and on mainland Europe. Possibly blatt der Bayerische Entomologen, 4: 91–93. changes of climate conditions have lead to more suitable Hochkirch A., Damerau M. 2009. Rapid range expansion of a habitat conditions for M. thalassinum. wing-dimorphic bush-cricket after the 2003 climatic anom- Third, unintentional introduction with material transports aly. Biological Journal of the Linnean Society, 97: 118–127. and/or hitchhiking on e.g. cars and ferries are a likely sce- Kleitou P., Giovos I., Wolf W., Crocetta F. 2019. 2019. On the im- nario for the recent occurrence of the Oak bush-cricket on portance of citizen-science: the first record of Goniobranchus the islands. Examples for such introductions are the Lesser obsoletus (Rüppel & Leuckart, 1830) from Cyprus (Mollusca: white-toothed Shrew Crocidura suaveolens (Pallas, 1811) Gastropoda: Nudibranchia). Bioinvasions Records, 8: 252–257. on Amrum and Föhr (Borkenhagen 2017) and the Common Schlenger H., Paffen K.H., Stewig R. 1969. Schleswig-Holstein. grass Snake Natrix natrix (Linnaeus, 1758) on Sylt (Böhme Ein geographisch landeskundlicher Exkursionsführer. Fest- & Grell 2013). We hypothesize that the combination of more schrift zum 37. Deutschen Geographentag 1969 in Kiel. Fer- suitable habitat conditions due to climate and landscape dinand Hirth, Kiel, 357 pp. change (extensive afforestations or settlement developments Schumacher R. 1980. Die einheimischen Laubheuschrecken. took part on all three islands) enabled unintended recent in- Berichte der naturhistorischen Gesellschaft Hannover, 123: troductions to successfully colonize the islands. The combi- 193–219. nation of monitoring and citizen science was particular use- Sutton P.G., Beckmann B.C., Nelson B. 2017. The current status of ful as effective tool for the detection of such a cryptic species orthopteroid insects in Britain and Ireland. Atropos, 59: 1–35. like the nocturnal and ‘silent’ Oak bush-cricket. Winkler C. 2000. Die Heuschrecken Schleswig-Holsteins – Rote Future investigations will provide information if the Liste. Landesamt für Natur und Umwelt des Landes Schle- Oak bush-cricket was also able to establish on other Ger- swig-Holstein, Kiel, 52 pp. man and Danish North Sea islands. It will need an inte- Winkler C., Haacks M. 2019. Die Heuschrecken Schleswig-Hol- grative approach to evaluate if M. thalassinum has been steins. Rote Liste. Landesamt für Landwirtschaft, Umwelt und overlooked so far or if the occurrence of this species was a ländliche Räume des Landes Schleswig-Holstein, Kiel, 85 pp. recent event. In latter case, to determine the founder pop- Winkler C., Klinge A. 2019. Die Heuschrecken Schleswig-Hol- ulation(s) of the oak bush-cricket, detailed genetic investi- steins, Arbeitsatlas. Available from https://www.foeag.de/ar- gations will be needed. tengruppen/heuschrecken (Accessed at 22 Sept. 2020).

Acknowledgements – We would like to thank Nina Drews, Martina & Helmut Finkh, Thees Jagles, Claudia Jung, Lotte von Komorski, Anja Rappen, Lillith Schlöbcke, Jannes Schulz and Kai Wechsung for providing information and photographs and Christian Winkler for many helpful comments.

References Borkenhagen P. 2017. Spitzmäuse (Soricidae) auf schleswig-hol- steinischen Nordsee-Inseln. Schriften des naturwissenschaft- lichen Vereins Schleswig-Holsteins, 75: 3–18. Böhme W., Grell O. 2013. Ringelnattern, Natrix natrix (Linnae- us, 1758), auf Sylt (Schleswig-Holstein): eingeschleppt aus verschiedenen Ländern? Faunistisch-Ökologische Mitteilun- gen, 9: 311–317. Christiansen W., Schmidtendorf H. 1952. Zur Frage des Atlan- tischen Klimakeils in Schleswig-Holstein und zur pflanzenge-

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